public class replaceWrite0 {
    public void duplicateZeros(int[] arr) {
        int dest=-1;
        int cur=0;
        int n=arr.length;
        while(cur<n){
            if(arr[cur]==0){
                dest+=2;
            }else{
                dest++;
            }
            if(dest>=n-1){
                break;
            }
            cur++;
        }

        if(dest==n){
            arr[n-1]=0;
            cur--;
            dest-=2;
        }
        while(cur>=0){
            if(arr[cur]!=0){
                arr[dest--]=arr[cur--];
            }else{
                arr[dest--]=0;
                arr[dest--]=0;
                cur--;
            }
        }
    }

    public static void main(String[] args) {
        
    }
}
